The potato is the world's foremost important food crop and by far the most important vegetable. Potatoes are currently grown commercially in nearly every state of the United States. Annual potato production exceeds 18 million tons in the United States and 300 million tons worldwide. The popularity of the potato derives mainly from its versatility and nutritional value. Potatoes can be used fresh, frozen or dried, or can be processed into flour, starch or alcohol. They contain complex carbohydrates and are rich in calcium, niacin and vitamin C. The U.S. acreage planted in potatoes has declined since the 1960's and 1970's, and this decline, coupled with increasing consumption, must be offset by higher usable yields. In some areas, diseases and pests damage crops despite the use of herbicides and pesticides.
It is generally recognized that quality seed potato stocks, usually identified as “Certified Seed”, are an essential component of profitable potato production enterprises. The use of such seed stocks is critical to the financial success of these enterprises because potatoes are one of the few vegetatively propagated crop species. Consequently, any disease introduction into the seed potato stock material is present in all successive propagations with its consequent deleterious impact because the potato tuber is a vegetative organ rather than a seed organ.
A number of schemes have been developed to minimize the impact of diseases on the commercial value of seed potato stocks. Such schemes are based on starting with tissue cultures of disease-free material in a sterile laboratory environment followed by growing out these established tissue cultures in greenhouse or outdoor screenhouse conditions. These schemes are described in a number of articles in the potato research literature including Struik, 1991, Struik and Wiersma, 1999, and Pruski, et al, 2003. A slightly different scheme is used by the Wisconsin Seed Potato Certification Program Department of Plant Pathology, University of Wisconsin-Madison, 1630 Linden Drive, Madison, Wis. 53706, for the generation of “Elite Foundation Seed” and subsequent sale to certified seed potato growers. This involves the identification of pathogen-negative material that is maintained on long-term tissue culture media in the form of microtubers. Each year, these “clones” are subcultured into thousands of plants, which are planted in a protected screenhouse for generation of tubers. These tubers are further propagated in the field and become the “Elite Foundation Seed”.
The schemes described in the published literature have several inherent limitations. These limitations include, limiting the amount of seed stock material that can be produced in any given calendar year, and the cost of producing such seed stock material. The greenhouse-based schemes provide at most two tuber harvests per year, even in geographic regions where the winter months of the year are not too cold. The screenhouse based schemes are limited essentially to only one tuber harvest per year. Both the greenhouse and screenhouse schemes have a high degree of probability of inadvertent insect infestation, such as aphids and leafhoppers that are vectors of serious potato diseases. The low production results of the schemes also reduce the availability of sizable seed stocks of new cultivars to commercial potato enterprises.
A method for producing potato minitubers is known from U.S. Pat. No. 5,419,079 issued May 30, 1995 to Wang et al. This patent sets forth a multiplicity of procedural method steps affecting the environmental and nutritional conditions of potato cuttings being propagated. This scheme, however, requires that all method steps are performed manually and without any automatic monitoring and control of the environment so that it is highly labor intensive and totally non-reactive. In addition, the cuttings must be placed in a shed built with frames and plastic film in a greenhouse after which the film is manipulated, all of which is cumbersome and inefficient. All control of temperature, lighting, humidity and nutrients occurs without any feedback during the propagation process. It is questionable that such manually controlled scheme will produce in a consistent and fast manner and without complications, as claimed, particularly in any geographic location.
Other computerized plant growing systems are known, but none are designed to optimize growth of potato plants over an entire life cycle.